Systematic Veterinary Bacteriology and Mycology

CULTURAL CHARACTERISTICS

• Mycobacterium avium subsp paratuberculosis requires mycobactin - Killed extract of M.phelei or other killed acid-fast organism- enriched media for growth.
• Slants of Herrold’s egg yolk medium with mycobactin are highly suitable for isolation of organism from specimens.
• The slants are incubated at 37⁰C for upto 16 weeks and examined weekly for evidence of growth.
• They produce minute grayish white, friable, irregular colonies, less than 1 mm in d.m., in 5-16 weeks. Isolates from sheep may be pigmented.